She will leave Rio with five total medals and two world records, adding four golds and a silver to the gold medal she won in London four years ago. Phelps meanwhile, holds an Olympic-record 23 gold medals and 28 overall, including five gold medals won in Rio.

As he wraps up what he said will be his last Olympics, Phelps, 31, said he believes the future of USA swimming is in good hands.

"Katie's doing her thing and she's breaking records every time she gets in the pool,” he told “Today's" Matt Lauer. “It's been an honor for me to be a part of the team with her and some of the younger guys that we have coming up in the sport that are going to take over."

He said he'll be in Tokyo in 2020, but will be cheering on Team USA from the stands not the pool.

Gymnasts Simone Biles and Laure Hernadez also recreated an old photo they took together, smiling broadly in both. Biles posted the two photos on Twitter Monday, just hours befor the two were set to compete at the beam finals. "Who wouldve thought WAY back then we would be competing in Beam finals together at the Olympics. DREAM BIG, she wrote.

who wouldve thought WAY back then we would be competing in Beam finals together at the Olympics 😱🇺🇸 •DREAM BIG• pic.twitter.com/dSaYBd1YtB